The present invention relates to a method and an apparatus for improving the crushing action of demolition tools, which include a carrier body on which two cooperating jaws, shears or tongs (hereafter collectively also referred to as "jaws") are mounted for engaging, from opposite sides, the matter to be crushed. At least one of the jaws is driven and is thus movable relative to the carrier body.
The drive unit which operates the demolition jaw or jaws and which also generates the necessary closing force during the crushing process may have any desired construction. In present-day demolition tools the drive unit is usually composed of one or more cylinder units with which one jaw is operated or both jaws are driven simultaneously.
German Patent 3,342,305 to which corresponds U.S. Pat. No. 4,512,524 discloses a concrete crusher which includes two jaws that are movably supported by a carrier body and which are each driven by means of a hydraulic cylinder unit.
In contrast thereto, the demolition shears disclosed in European Patent Application 218,899 includes only one movable shearing arm and a drive unit composed of one cylinder unit; the second shearing arm is immovably fastened to the carrier body.
Demolition tools of the type under discussion (demolition jaws or demolition shears) represent in many cases, particularly in the demolition and reconstruction of buildings, an effective alternative to a hydraulic/pneumatic percussion mechanism, a steel ball or explosives. The discussed demolition tools are advantageous in that they operate with low noise and are capable of crushing metal reinforcements and separating--for the purpose of reprocessing/recycling--the different construction materials that are encountered during the crushing process.
The demolition tools according to the prior art are similar insofar as they each generate a continuously active closing force. In crushing concrete or the like, with or without metal reinforcements, in certain work situations the breaking and cutting force exerted by the demolition tool does not produce the desired result. Consequently, frequent changes of position, readjustments and restarting of the demolition tool are required which may lead to a reduction of efficiency and output.